In a healthy patient, the lungs provide oxygen to the blood and remove carbon dioxide. However, in patients with severe lung failure, blood may not adequately be delivered to the lungs, or the lungs may not adequately supply blood with oxygen. In this case, patients may require assistance from a machine to help provide this oxygen. Extracorporeal membrane oxygenation (ECMO) is a device that acts as an artificial lung, allowing the patient to recover from their illness. Patients receiving support from ECMO are often put in a medically induced coma while their lungs heal. Certain drugs may stick to the internal surfaces of the machine; therefore leading to decreased concentrations. Patients receiving ECMO often require high doses of both pain medications and sedatives in order to provide comfort. Low doses of a drug, ketamine, may help to provide additive effects to pain relief and allow lower doses of other pain medications. The hypothesis is that patients treated with continuous intravenous ketamine, will have lower requirements of other pain medications while receiving ECMO for acute respiratory failure while achieving the desired level of sedation.